1. Field of the Invention
The present invention relates to an optical coherence tomography, and more particularly, an optical coherence tomography using an active mode-locking fiber laser having a center wavelength which is changed by a high speed repeated scanning.
2. Description of the Related Art
A detecting system using a light space division comprises an optical coherence tomography (OCT) obtaining an image-in-depth of a sample with the coherence of light. The optical coherence tomography is a high-resolution imaging system capable of imaging of internal tissue of a sample. The optical coherence tomography uses interference of a light source in near infrared ray wavelength. Particularly, the optical coherence tomography does not contact the inside of a sample for imaging, and recently, the related studies have been actively conducting.
In the optical coherence tomography, an acquisition rate of information in depth direction is dependent on a repetition rate of a center wavelength variable laser. Unlikely, the scanning along a horizontal axis and a vertical axis should be done when obtaining two-dimensional or three-dimensional image from the optical coherence tomography.
Thus, conventional optical coherence tomography requires an optical variable filter to periodically scan laser wavelength and convert wavelength. Fabry-perot filter is mainly used for this optical variable filter.
Meanwhile, there is a problem of degradation characteristics of the optical variable filter with mechanical restrictions in the frequency domain over hundreds of kHz. Also, these optical variable filters are relatively expensive, and cost of producing optical coherence tomography increases.